/Engine/Source/Runtime/MessagingRpc/Public/MessageRpcServer.h
Send a progress message to the RPC client that made the RPC call.
void SendProgress ( const [FGuid](API\Runtime\Core\Misc\FGuid) & CallId, const [FReturnInfo](API\Runtime\MessagingRpc\FMessageRpcServer\FReturnInfo) & ReturnInfo )